Diagnosing Breast Cancer: What You Need to Know About Invasive and Non-Invasive Techniques

Survival is highest when breast cancer is diagnosed and treated at an early stage. Several imaging modalities may be used to do so. The American Cancer Society recommends the following for breast cancer screening:[1]

Age 20 and above: monthly breast self–exam and yearly clinical breast exams (CBE) by a physician

Age 35 – 39: A baseline mammogram should be done during this time along with a yearly CBE

Ages 40-49: Mammogram every 1-2 years and yearly CBE

Ages 50 and above: Yearly mammogram and CBE

Some say that a tumor must be at least 1 cm to be palpable, or felt on physical exam. As a result, CBE can miss some breast cancers, which give further importance to the imaging adjuncts listed below.

Imaging

Mammography

A mammogram is a special kind of X-ray that is taken as the breast is compressed between two plates, spreading out the tissue to evaluate its structure. Mammography can detect cysts, masses and calcifications. However, some studies show that mammography may miss up to 35% of cancer diagnoses.[2] This is most often in dense breast tissue which may require other types of imaging to make a diagnosis.

Ultrasound

Ultrasound is a non-invasive modality that does not use radiation. High frequency sound waves are sent through a probe, which is placed on the skin with a thin layer of gel that acts as a medium through which the sound waves travel. As the sound waves deflect off of different types of tissue, an image is created on a monitor. Different types of tissues have varying densities which changes the way sound waves deflect, allowing the technician to determine characteristics about the tissue. [3] This is similar to sonar technology used by submarines to determine their location and presence of other objects under the water.

MRI

MRI is also non-invasive and does not use radiation, but high-powered magnets that spin rapidly in a circular motion. Different tissues have variable amounts of water in them and MRI detects the hydrogen molecules in tissue and projects this information onto a monitor. The result is a 3-D image that clearly defines types of tissue. Not everyone can have an MRI and although useful, its function in breast cancer screening is yet to be clearly defined.[4] It is particularly useful when evaluating the contralateral breast for cancer when it has already been diagnosed on one side.

Procedures

Biopsy

When imaging has failed to prove or disprove that cancer is present or when cancer is highly suspicious, a biopsy can be done. A piece of tissue is taken and a pathologist puts the tissue on glass slides and looks at it under a microscope to evaluate for the presence of cancer.

Conclusion

With so many diagnostic techniques available, why is breast cancer still the second leading cause of cancer-related death in women? The answer is not clear, but we have seen a steady decline in the incidence and mortality of breast cancer since the importance of screening has been illuminated.

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